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Understanding The Meteorology Of A Fly Ball May Help Baseball Teams

As I write this, the World Series opener is only a few hours away. Two storied Major League Baseball (MLB) franchises, the Los Angeles Dodgers and Boston Red Sox, play in the fall classic. Both teams play in outdoor stadiums so there is always a chance that weather will be a factor. However, I decided to go beyond the standard story about how weather might affect the World Series. As an atmospheric scientist, I thought it would be interesting to explore the meteorology of actual baseballs in flight and the innovative capabilities of a new company called Weather Applied Metrics.

Impact of a crosswind on a fly ball.

John Farley/WAM

To explore this topic, I had a conversation with John Farley, the Chief Technology Officer for Weather Applied Metrics (see this link for an information video). The company quantifies weather impacts on baseball (and sports in general) using Computational Fluid Dynamics (CFD) modeling, standard trajectory physics, and other meteorological analysis. According to Farley, the company has a team of six: two PhDs - one is a retired meteorology professor, one is a CFD engineer, one master's degree meteorologist, a college physics student, a CEO of a Silicon Valley Company, and a San Francisco Bay Area broadcast meteorologist. Farley reached out to me, and I was immediately fascinated. In my scholarly research, I study urban meteorological processes so was familiar with the use of Computational Fluid Dynamics modeling (good tutorial at this link) to simulate flow around buildings or to track tracer flows for hazardous materials. There are many applications of CFDs, but I really never thought one would be at a baseball stadium. Weather Applied Metrics installed its Beta site at the Columbia Fireflies stadium. The Fireflies are the Single A Affiliate of the New York Mets in Columbia, South Carolina. Farley told me,

You may recall that Tim Tebow hit a home run in his first at bat with the Fireflies. That day the weather helped carry that ball by roughly 15-18 feet and it cleared the fence by a few feet. So without the weather, it would probably have been a warning track out. Last June we installed our technology in an MLB park and we are now in the final stages of completing an agreement with them for the 2019 season.

I was so fascinated by what this company was up to that I conducted a Q & A with Farley. Our conversation is summarized below.

John Farley: If the wind is blowing hard, that's the most significant impact. A headwind, combined with a downdraft, can shorten a fly ball hit to the wall by as much as 60 feet. A tail wind, combined with an updraft can lengthen it by as much as 45 feet. Since baseballs absorb moisture from the air (they are hygroscopic), the difference in distance between very dry air and very wet air is roughly 50 feet. That's because a wet ball is slightly heavier and spongier, so it doesn't come off the bat as fast. On a hotter day the air is less dense and so a ball can travel as much as 30 feet farther, compared to a cold day. Air pressure affects density directly. So balls hit at high altitude travel considerably farther. In the graphic above, our analysis is an example of a cross wind over a major league stadium. With the resulting downdraft and headwind in right field, the ball’s flight is shortened by roughly 30 feet.

Dr. Marshall Shepherd: Can it significantly impact outcomes and is there a way of determining?

John Farley: Yes. Our real-time display at the Fireflies Stadium in Columbia, SC shows how much the weather is impacting the distance of an average fly ball hit to the outfield fence (averaging 375 feet). Blue numbers are feet added. Red numbers are feet subtracted. Here are a few examples from games. The arrow at home plate shows the prevailing wind. In this smaller stadium, the prevailing wind is very representative of the winds over the flight of the ball.

Examples of impacts on a fly ball based on analysis by Weather Applied Metrics

John Farley

Dr. Marshall Shepherd: How are you using Computation Fluid Dynamics (CFD) Modeling to study baseball?

John Farley: CFD is necessary because the wind flow inside stadiums is very complex and often very different from what the flags show on top of the stadium. Additionally, what’s been missing from all of the baseball trajectory analysis that we’ve seen is vertical wind (as meteorologists that’s all we think about!). And there is a lot of vertical wind inside stadiums, which has a significant impact on the flight of the ball over its entire trajectory. Prevailing winds (see graphic below) blowing over a stadium in one direction, but the winds at field level doing the exact opposite, and there’s a lot going on in between. We model the wind field down to each square foot over the entire area where a ball could fly. Then we use those winds for our 3D-Trajectory model with increments of 0.001 seconds.

Computational Fluid Dynamics modeling at a baseball stadium

John Farley

Dr. Marshall Shepherd: Why are you doing this?

John Farley: We are weather and sports geeks and we are very curious! Why else would we do this? ;-) As meteorologists, we’ve always know that weather has a huge impact on sports. Now we can tell you exactly what’s going on with each ball.

Farley and colleagues may be on to something, but only time will tell. He provided me with a summary of how Weather Applied Metrics (WAM) illustrates the impact of weather on baseball. Data was collected for all home games for the Columbia South Carolina Fireflies for the 2016 Season. The bulk game statistics show some pretty compelling impacts on runs per game, earned runs per game, home runs per game, and hits per game.

Dr. J. Marshall Shepherd, a leading international expert in weather and climate, was the 2013 President of American Meteorological Society (AMS) and is Director of the

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Dr. J. Marshall Shepherd, a leading international expert in weather and climate, was the 2013 President of American Meteorological Society (AMS) and is Director of the University of Georgia’s (UGA) Atmospheric Sciences Program. Dr. Shepherd is the Georgia Athletic Association Distinguished Professor and hosts The Weather Channel’s Weather Geeks Podcast, which can be found at all podcast outlets. Prior to UGA, Dr. Shepherd spent 12 years as a Research Meteorologist at NASA-Goddard Space Flight Center and was Deputy Project Scientist for the Global Precipitation Measurement (GPM) mission. In 2004, he was honored at the White House with a prestigious PECASE award. He also has received major honors from the American Meteorological Society, American Association of Geographers, and the Captain Planet Foundation. Shepherd is frequently sought as an expert on weather and climate by major media outlets, the White House, and Congress. He has over 80 peer-reviewed scholarly publications and numerous editorials. Dr. Shepherd received his B.S., M.S. and PhD in physical meteorology from Florida State University.